Thermal recording head and drive circuit

ABSTRACT

A recording apparatus includes a recording head and a drive circuit for driving the recording head. The recording head includes a plurality of main blocks arranged successively in a given direction and a plurality of first and second conductors. The main blocks each include first and second unit recording blocks arranged in the given direction. Each unit recording block includes n recording units arranged in the given direction. One ends of the n recording units are collectively connected to the selection terminal of each unit recording block. The first conductors each connect the other end of the ith (n≧i≧1) of the first recording block with the other end of the (n+1-i)th recording unit of the second unit recording block. The second conductors connect the corresponding first conductors in the respective main blocks and bears thereon signals to be recorded. The drive circuit includes first means for selecting a desired one of the unit recording blocks and second means for supplying recording signals to the recording units of the selected unit recording block in the order of the given directional order.

The present invention relates to a recording apparatus and more particularly to a thermal recording apparatus.

Recently, facsimiles, printers and the like have employed as recording means a thermal recording apparatus for recording information on a heat sensitive paper by using a recording head with a number of heating resistors serially arranged.

In such a recording apparatus, several hundreds to one thousand recording units are arranged in a row, so that connection between the recording units and its drive circuit is considerably complicated. For simplification of the complicated connection, a diode matrix circuit as shown in FIG. 1 is used to successfully reduce the connecting portions. As shown, a plurality of unit recording blocks UB₁, UB₂, UB₃, . . . are serially arranged in a given direction. Each recording unit includes n recording units successively arranged in the block arrangement direction each of which further includes a heating resistor R and a diode D with the polarity as shown these being connected in series. The recording units of n are connected collectively at one ends to a selection terminal of the corresponding unit recording block. For example, one ends of the recording units of the first unit recording block UB₁, i.e. one ends of the heating resistors R₁₁ to R_(1n), are connected to a selection terminal C₁ ; one ends of the recording units of the second unit recording block UB₂, i.e. one ends of the heating resistors R₂₁ to R_(2n) to a selection terminal C₂ ; likewise, one ends of the heating resistors R₂₁ to R_(2n) to a selection terminal C₃. Recording signal feeding lines L₁ to L_(n) are correspondingly connected to the cathodes of the diodes of each unit recording block, as shown in FIG. 1. These cathodes form the other ends of the first to nth recording units of each unit recording block. A drive circuit (not shown) is connected at the recording signal feeding terminals to the lines L₁ to L_(n) and the unit recording block selection terminals to the corresponding selection terminals C₁ to C_(n) of the recording unit blocks. In this connection scheme, number of connection lines connecting heating resistors to diode matrices equals to that of all the heating resistors, however. The connection scheme still suffers from complex connection work. Directed to overcome this problem, another method was developed in which the respective ends of a flexible cable with parallel conductors densely printed thereon are pressured onto the other ends of the heating resistors and a substrate on which the diodes matrices circuit is printed and the diodes are mounted. However, this method provides another new problem of bulkiness of the recording head, being still accompanied by the above-mentioned problem of complex connection work.

A multilayer printing method by using thick film technology was developed to solve such the complexity of the connection, see FIG. 2. In this method, diodes are mounted on an insulating substrate 1 and the matrices wiring associated with the diodes are printed thereon by using the multi-layer wiring method. In the figure, only the multi-layered wiring is depicted. First conductors 1₁₁ to 1_(1n), 1₂₁ to 1_(2n), . . . are connected to the diodes D₁₁ to D_(1n), D₂₁ to D_(2n), . . . , respectively, and these conductors are printed with the same interval as of the heating resistors. The conductor density is 4 lines per mm to 6 lines per mm so that the interval P₁ of the first conductors is 167 to 250μm. The terminals 2 of the first conductors belonging to a unit recording block are disposed aligning with a dotted line 3 slanted. Insulating layers 4 are printed so as to cover these lines 3. Second conductors (recording signal feeding lines) L₁ to L_(n) are printed on these insulating layers 4. Each of these second conductors is disposed normal to the corresponding conductor (with the same line order as of the first conductor) of each unit recording block at the terminal 2 of the first conductor. At these cross points, holes 5 are formed to the insulating layer 4. By inserting a conductor into each of these holes 5, the first conductors with the same order of the conductor disposition of the respective unit recording blocks are connected commonly to a single second conductor with the corresponding disposition order.

To ensure the connection of the first conductors with the second conductors, the diameter of each hole 5 must be larger than the width of the first conductor. Therefore, there is a possibility that the periphery of the hole 5 comes in contact with the first conductor neighbouring with the hole 5. The experiment conducted by the inventors of the present application showed that, when the interval P₁ between adjacent first conductors is less than 200μm, the contact accidents take place very frequently, reducing the yield of the recording head manufacturing. Further, to reduce the contact accidents, the interval P₁ must be at least 300μm. As previously stated, the interval P₁ is 167 to 250μm and therefore, in order to secure more than 300μm of the interval P₁, the intervals of the first conductors must be widened midway between the extremes of interval. Adversely, the widening of the intervals lead to bulkiness of the recording head, however.

As seen from the foregoing, the conventional techniques are troubled with a contradiction that the miniaturization of the recording head reduces the yield of its manufacturing while improvement of the yield brings about bulkiness of the recording head.

Accordingly, the primary object of the present invention is to provide a recording apparatus of which the recording head may be made small in size and with improved yields.

According to the present invention, there is provided a recording apparatus comprising a recording head including a plurality of main blocks arranged in a given direction each main block having first and second unit recording blocks arranged in the given direction each unit recording block further including n recording units each recording unit further including a series-connected diode and recording element pair, a plurality of unit recording block selection terminals each of which is connected to one ends of the n recording units, a plurality of first conductors for connecting the other ends of the ith (n≧i≧1) recording units of the first unit recording block with the other ends of the (n+1-i)th recording units of the second unit recording block, and a plurality of second conductors for connecting commonly the corresponding first conductors among the main blocks and for supplying signals to be recorded to the recording units; and a drive circuit including first means for selecting a desired one of the unit recording blocks and second means for supplying recording signals in the order of the recording units arrangement to the recording units of the selected unit recording block.

Other objects and features of the invention will be apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 shows a wiring diagram of a recording head of a conventional recording apparatus;

FIG. 2 is an enlarged view of a part of the connection scheme of the recording head shown in FIG. 1;

FIG. 3 is a wiring diagram of a recording head of a recording apparatus according to the present invention;

FIG. 4 is an enlarged view of a part of the connection scheme of the FIG. 3 recording head;

FIG. 5 is a plan view of a modification of the FIG. 4 wiring scheme shown in FIG. 4;

FIG. 6 is a perspective view of an enlarged view of a part of the FIG. 5 connection scheme;

FIG. 7 is circuit diagram illustrating one form of the connection schemes of the recording head shown in FIG. 3 with a drive circuit for it, in which number of the recording units in each unit recording block is 7;

FIG. 8 is a circuit diagram illustrating the details of a part of the FIG. 7 circuit;

FIG. 9 is a set of timing charts for illustrating the operation of the FIG. 7 circuit;

FIG. 10 is a modification of the drive circuit of FIG. 7; and

FIG. 11 is another modification of the drive circuit of FIG. 7.

In the following figures, the same parts are denoted by the same reference numbers as those of FIGS. 1 and 2.

As shown in FIG. 3, main blocks MB₁ and MB₂ are arranged successively to the right as viewed in the drawing. The main block MB₁ includes first and second unit recording blocks UB₁ and UB₂ disposed in consecutive order to the right as viewed in the drawing. This is correspondingly applied to the other main blocks MB₂ and MB₃. A heating resistor, for example, R₁₁ and a diode, for example, D₁₁ are connected in series and these constitute a recording unit. Each of the recording blocks includes n recording units arranged in series order as in the same direction as of the respective unit recording blocks UB₁ and UB₂ disposition. One ends of the n recording units of each unit recording blocks are connected a selection terminal C₁, C₂, . . . of each unit recording block. In each main block, the other end of the ith (n≧i≧1) recording unit of the first unit recording block, for example, UB₁ and the other end of the (n+ 1-i)th recording unit of the second unit recording block are connected by a first conductor. In the figure, the first portion of the first conductor includes conductors 1₁₁ and 1_(2n) and the second portion thereof is illustrated including a conductor connecting the free ends of the conductors 1₁₁ and 1_(2n). The corresponding second portions of the first conductors in the respective main blocks MB₁, MB₂, . . . are connected to recording signal feeding lines L₁, L₂, . . . L_(n). The diode may be inserted between a recording element and a unit recording block selection terminal.

FIG. 4 shows a plan view of the matrix wiring portion of the recording head shown in FIG. 3 when it is fabricated by the thick multi-layer printing method. On an insulating substrate 11, recording elements R₁₁ to R_(1n), R₂₁ to R_(2n), . . . and diodes D₁₁ to D_(1n), D₂₁ to D_(2n), . . . (not shown) are provided and the first portion 1₁₁ to 1_(1n), 1₂₁ to 1_(2n), . . . of the first conductor which are connected to respective cathodes of diodes D₁₁ to D_(1n), D₂₁ to D_(2n), . . . , are formed thereon by means of the thick film printing technology. The first portion, i.e. conductors 1₁₁ to 1_(1n), 1₂₁ to 1_(2n), . . . , are disposed in parallel and the interval P₁ therebetween are selected 167 to 250μm (the interval density 4 lines per mm to 6 lines per mm). The second portion of the first conductor is disposed normal to the first portion. The interval P₂ of the second portion is selected 300μm or more. An insulating layer 12 is formed by the thick film printing method so as to cover the entire of the second portion. The first conductor group of the main blocks MB₁ and MB₂, . . . are designated by character l. The insulating layer 12 is provided with a hole 13 at the portion corresponding to the almost center of the second portion of each first conductor. The hole 13 is filled with a conductor. On the insulating layer 12, second conductors L₁, L₂, . . . L_(n) (recording signal feeding lines) are formed by the thick film printing method. These second conductors pass through the hole 13 and coupled with the conductors of the holes and parallel with the second portion of the first conductor. The group of the second conductor is designated by character L.

As seen from FIG. 4, the distance between the connecting portion 13 connecting the first conductor l with the second conductor L and the first portion of the first conductor closest to the connecting portion 13 may be substantially three times that of the FIG. 2 case. Therefore, the interval P₁ of the first portion of the first conductor satisfactorily prevents shortcircuiting between the first conductors, even with its value of 167μm. This enables the yield of the recording head manufacturing to be improved and the size of the recording head to be small. As seen from FIG. 3, number of the connecting points between the first conductor l and the second conductor L in n×m/2 (n is number of the recording units in each unit recording block and m is number of the unit recording blocks), the number is half that of the FIG. 1 or FIG. 2 case. This means that the manufacturing process of the recording head is simplified, the yield is improved and the reliability of it is enhanced.

The recording head of the invention may be modified to those shown in FIGS. 5 and 6. In FIG. 5, the printing process of the first conductor l onto the insulating substrate 11 (FIG. 4) is much the same as that of the previous case, thus omitting the illustration of it. In this embodiment, flexible film 15 is used instead of an insulating layer 12. (See FIG. 4). The flexible film 15 is a polyimide film of 30 to 100μm thick. The film 15 is printed on the insulating substrate 11 (FIG. 4) so as to cover the entire of the second portion of the second conductor l in FIG. 4. On the film 15, a copper film with 50 to 100μm thick is formed and then unnecessary portion thereof is removed by etching method, to form the second conductor L. The film 15 is provided with an elongated hole 16 at the portion corresponding to the hole 13 of FIG. 4. The first conductor l and the second conductor L are connected by soldering through the elongated hole 16. FIG. 6 shows an enlargement of the connecting portion of the first conductor l and the second conductor L. In the figure, the number n of the recording units is assumed to be 6.

In the FIG. 5 embodiment, the film 15 includes extensions 15a and 15a. On the major land of the film 15, the second conductor L are alternately portioned out to the right and left sides and directly connected at both ends to connectors (not shown). The alternate portioning out makes substantially uniform the resistances of the conductors extending to the heating resistors. Therefore, the density of the recording information on the recording paper may be made uniform.

As seen from FIG. 3, the connection orders of the recording units to the second conductor L in the respective adjacent unit recording blocks are reversed each other. More specifically, the 1st to nth recording units in the first recording block UB₁ are connected to the L₁ to L_(n) conductors of the 2nd conductors, respectively. In the second unit recording block UB₂, the 1st to nth recording units are correspondingly connected to the L_(n) to L₁ conductors, respectively. Therefore, if a series of recording signals to be fed in the order of the recording unit arrangement (for example, image formation signal) is applied to the second conductors in the order of L₁, L₂, . . . L_(n), the image formed by the odd numbered unit recording blocks UB₁, UB₃, . . . and that by the even numbered unit recording blocks UB₂, UB₄, . . . are related in reversed fashion. Accordingly, the recording head shown in FIG. 3 must be driven so as not to avoid the image inversion.

Turning now to FIG. 7, there is shown one form of connection schemes of the recording head RH shown in FIG. 3 and a drive circuit DR. In this example, number n of the recording units is 7. The drive circuit DR includes; first and second shift registers SR₁ and SR₂ ; a unit recording block selection circuit 20; drive means to drive first and second shift registers SR₁ and SR₂ ; AND gate groups 21 and 22 for reading out the outputs of shift registers SR₁ and SR₂, respectively; an OR gate group for receiving the outputs of the AND gate groups 21 and 22; and a transistor circuit 24 driven by the output of the OR gate group 23. The unit recording block selection circuit 20 received a selection circuit control signal SC and produces unit recording block selection signals UBC₁, UBC₂, . . . . These unit recording block selection signals are applied to the gate terminals of transistors TR₁, TR₂, . . . , respectively. The emitters of these transistors are commonly connected to +V source. The collectors are coupled with the unit recording block selection terminals C₁, C₂, . . . . The outputs of the OR gates of the OR gate group 23 are connected to the gates of the corresponding transistors of the transistor driving circuit 24, respectively. The emitters of the transistors 24-1 to 24-7 are earthed and the collectors are connected to the second conductors L₁ to L_(n) in this order, respectively.

The first and second shift register SR₁ and SR₂, their driving means and the gate groups at the output side thereof are detailed in FIG. 8. As mentioned above, 7 recording units are used in this example so that the contents of the shift registers SR₁ and SR₂ are each constructed by 7 bits. A picture signal S_(O) is binary signals serially supplied and is supplied to the shift registers SR₁ and SR₂. Assume here that the signal supply is made in the serial order of Q₁ to Q₇ and Q'₁ to Q'₇. S₁ is a shift pulse which is used when the picture signal S_(O) is loaded into the respective registers, and is applied to one of the inputs of each AND gates G₁ and G₂. S₂ is a selection pulse for selecting either of the shift registers SR₁ and SR₂ and applied to the other input of the AND gate G₁, an inverter G₃ and the AND gate group 22. The output of the inverter G₃ is applied to the other input of the AND gate G₂ and the input of the AND gate group 21. The outputs of the AND gates G₁ and G₂ are applied as shift pulses to the shift registers SR₁ and SR₂. Each shift register produces outputs from the respective stages thereof and in this example it produces 7 outputs. As shown, the shift registers each produce 1st to 7th outputs as counted from the right hand side. The ith (n≧i≧1) output of the shift register SR₁ and the (n+1-i)th output of the shift register SR₂ are coupled with the corresponding first conductor through a single OR gate. With an arrangement, as shown, of the AND gate group 21 including AND gates G₁₁ to G₁₇, the AND gate group 22 including AND gates G₂₁ to G₂₇, and the OR gate group including OR gates G₃₁ to G₃₇, the outputs of the OR gates G₃₁ to G₃₇ are correspondingly coupled with the first conductors L₁ to L_(n), respectively. The recording signal with the contents Q₁ to Q₇ and Q'₁ to Q'₇ are fed to the drive circuit in the order of Q₁ to Q₇ and Q'₁ to Q'₇. The shift register SR₁ and SR₂ are shifted in an arrow direction.

The operation of the apparatus shown in FIG. 7 will be described with reference to FIGS. 8 and 9. An example to be given is the case where the unit recording blocks UB₁, UB₂, . . . are successively selected in the order of the designations of the blocks. When the unit recording block selection circuit 20 is driven, it produces pulses UBC₁, UBC₂, UBC₃, . . . to successively select the unit recording blocks which in turn drive transistors TR₁, TR₂, TR₃, . . . to select sequentially the unit recording blocks UB₁, UB₂, UB₃, . . . . The shift register selection signal S₂, in order to drive the shift registers SR₁ and SR₂, is transferred to the gate G₁, the inverter G₃ and the gate group 22. As shown in FIG. 9, the selection signal S₂ has alternately and serially arranged "1" and "0" and the time widths of "1" and "0" are equal. The shift register selection signal S₂ and the unit recording block selection pulses UBC₁, UBC₂, UBC₃, . . . are synchronized in a predetermined relation. That is, the unit recording block selection pulses UBC₁, UBC₂, UBC₃, . . . are produced at the time period S₂₂, S₂₃, S₂₄, . . . , respectively. During each time period S₂₁, S₂₂, . . . , seven shift pulses S₁ and seven recording signals S_(O) are applied to the respective shift registers. At time t₁, when the register selection signal S₂ is "1", the shift register SR₁ is selected and shifted in the arrow direction by the shift pulse S₁ fed through and AND gate G₁. The recording signal S_(O) is serially supplied to the shift register SR₁ so that the bits Q₁ to Q₇ of the recording signal S_(O) are loaded into the shift register SR₁ at the time periods S₂₁, as shown in the figure. At time t₂, when loading of it is completed, the register selection signal S₂ is "0" which passes through the inverter G₃ to reach as "1" the AND gates G₁₁ to G₁₇. Therefore, the recording signals Q₁ to Q₇ are transferred to the second conductors L₁ to L₇ through the OR gates G₃₁ to G₃₇. At time t₂, the unit recording block selection signal UBC₁ is "1" and therefore the recording signals Q₁ to Q₇ are supplied to the recording elements R₁₁ to R₁₇ to be recorded on a recording paper (not shown). At time t₂, the register selection signal S₂ is "0" and is inverted in the inverter G₃ to be "1". The inverted "1" signal is applied to the AND gate G₂. Upon the reception of the signal "1", the AND gate G₂ permits the shift register SR₂ to shift in the arrow direction and the recording signal Q'₁ to Q'₇ to be loaded into the register as shown in the figure. At time t₃, when the loading of it is completed, the shift register selection signal S₂ becomes again "1" and thus the recording signals Q'₁ to Q'₇ are applied through the AND gates G₂₁ to G₂₇ and the OR gates G₃₇ to G₃₁ to the second conductors L₇ to L₁. At time t₃, the selection signal UBC₂ of the unit recording block UB₂ is produced, and therefore the recording signals Q'₁ to Q'₇ are applied to the writing elements R₂₁ to R₂₇ of the unit writing block UB₂. In other words, the recording signals Q₁ to Q₇ and Q'₁ to Q'₇ are applied to the recording elements R₁₁ to R₁₇ and R₂₁ to R₂₇. In this manner, it is avoidable to reverse the records made by the unit recording blocks UB₁ and UB₂. Then, when the unit recording block UB₃ is selected, the signals to be recorded are successively supplied from the shift register SR₁ to the second conductors L₁ to L₇. In other words, the order in which serially incoming recording signals are supplied to the second conductors is reversed each time the unit recording block is selected with the result that the recording is normally made, i.e. avoiding the picture inversion.

In the description referring to FIG. 7, the unit recording blocks are selected in the order of the arrangement thereof; however, any one of the unit recording blocks may be selected. In this case, when the odd numbered unit recording block is selected, the contents of the first shift register SR₁ is recorded and when the even numbered unit recording block is selected, the contents of the second shift register SR₂ is recorded.

In the embodiment of FIG. 7, in order to alternately supply the outputs of the shift registers SR₁ and SR₂ to the second conductor L, the OR gate group 23 is provided between the shift registers SR₁ and SR₂ and the second conductor L. A modification of this is shown in FIG. 10, in which only the output of the shift register SR₂ is supplied to the second conductor L. This modification simplifies the circuit construction of the drive circuit and therefore is advantageous in the manufacturing process and the cost saving.

In FIG. 10, the recording signal S_(O) is inputted to the first shift register SR₁. Shift pulses S_(a) with first frequency and another shift pulses S_(b) with second frequency higher than the first one are applied to an OR gate G₄₀ of which the output is applied as shift pulses to the first shift register SR₁ of seven bits. Shift pulses S_(b) are applied as shift pulses to the second shift register SR₂ (Buffer Register). A recording signal S₄ fed from the first shift register SR₁ is applied to one of the inputs of each AND gate G₄₂ and G₄₃. A pulse S₃ for switching the shift direction of the second shift register SR₂ is applied to the second shift register SR₂ while at the same time to the other input of the AND gate G₄₂. The same pulse S₃ is applied to the other input of the AND gate G₄₃ through an inverter G₄₁.

Output pulse S₅ (a right-shift pulse) of the AND gate G₄₂ switches the shift direction of the shift register SR₂ to the right and serves as an input to the shift register SR₂ to load into the position shown in the figure the input signals Q₁ to Q₇, through the first shift register SR₁. Output pulse S₆ (a left-shift pulse) of the AND gate G₄₃ changes the shift direction of the shift register SR₂ to the left, thereby to load the input signals Q'₁ to Q'₇ into the position shown in the figure. The outputs of the 1st to 7th stages as counted from the right on the drawing are coupled with the bases of transistors TR₁ to TR₇, through resistors R₁ to R₇. The emitters of transistors TR₁ to TR₇ are connected commonly and the collectors thereof are connected to the second conductors L₁ to L₇. The recording signal S_(O), for example, Q₁ to Q₇ and Q'₁ to Q'₇, are serially inputted into the first shift register SR₁. In this case, the recording signals Q₁ to Q₇ are firstly loaded into the register SR₁ by the shift pulse S_(a). When the loading of it into the shift register SR₁ is completed, the pulse S₃ becomes "1" to change the shift direction of the shift register SR₂ to the right. At the same time, the shift pulse S_(b) feeds the recording signals Q₁ to Q₇ (S₄) stored in the register SR₁ to the AND gate G₄₂ and G₄₃. At this time, the shift direction switch pulse is "1" and therefore the AND gate G₄₂ is enabled. The output S₅ of the AND gate G₄₂ is connected to the right shift input of the register SR₂. For this, the shift pulse S_(b) transfers the contents Q₁ to Q₇ of the register SR₁ from the shift register SR₁ to SR₂ at high rate, through AND gate G₄₂.

The contents Q₁ to Q₇ of the register SR₂ are supplied to the second conductors L₁ to L₇. At this time, as described referring to FIG. 7, the odd numbered unit recording block, for example, UB₁, is selected so that the recording signals Q₁ to Q₇ are supplied to the writing elements R₁₁ to R₁₇ (see FIG. 7). Then, the recording signals Q'₁ to Q'₇ are loaded into the first shift register SR₁ by the shift pulse S_(a). Upon the completion of the loading, the pulse S₃ becomes "0" to change the shift direction of the register SR₂ to the left as viewed on the drawing. And the pulse S₃ passes through the inverter G₄₁ to one of the inputs of AND gate G₄₃, thereby to enable the gate G₄₃. Accordingly, the recording signals Q'₁ to Q'₇ (S₄) becomes an output signal S₆ to be applied as a left shift input signal of the shift register SR₂ to the register SR₂. At this time, the shift pulse S_(b) is applied to the registers SR₁ and SR₂ to permit the recording signals Q'₁ to Q'₇ to be transferred to the position shown in the FIGURE of the shift register SR₂. Accordingly, the recording signals Q'₁ to Q'₇ are delivered to the second conductors L₇ to L₁.

At this time, the unit writing block, for example, UB₂ (FIG. 7), is selected so that the recording signal Q'₁ to Q'₇ are applied to the writing elements R₂₁ to R₂₇. In this way, while the shift direction of the first shift register SR₁ is fixed, the shift direction of the second shift register SR₂ is reversed each time the unit recording block is selected. Through that operation, the recording signal may be recorded on the recording paper with normal relative positions of the pictures recorded.

FIG. 11 shows an example to reverse the shift direction of the first shift register SR₁ each time the unit recording block is selected. In the figure, the recording signal S₀ provides bit signals Q₁ to Q₇ and Q'₁ to Q'₇ in this order to the first shift register SR₁. The writing shift pulse S₁ is coupled with the shift register SR₁. The recording signal S₀ is supplied to one of the inputs of each AND gate G₄₂ and G₄₃, and the shift direction switching pulse S₃ is supplied to the other input of the AND gate G₄₂ and with the other input of the AND gate G₄₃ through an inverter G₄₁. The pulse S₃ is also coupled with the register SR₁ in order to change the shift direction of the register SR₁. The output S₅ of the AND gate G₄₂ is applied to the shift register SR₁ to be shifted to the right direction while the output S₆ of the AND gate G₄₂ is applied to the shift register SR₁ to be shifted to the left direction.

The contents of the shift register SR₁ are simultaneously transferred in parallel to the second shift register SR₂ by a writing control pulse S₇. The contents of the respective stages of the second shift register SR₂ are delivered to the second conductors L₁ to L₇, in response to the writing control pulse S₇. The shift direction switching pulse S₃ "1" and the output of the AND gate G₄₂ cooperate to load the recording signals Q₁ to Q₇ into the position as shown of the register SR₁. The writing control pulse S₇ transfers in parallel the loaded contents to the second conductors L₁ to L₇. At this time, the odd numbered recording block, for example, UB₁, is selected so that the recording signals Q₁ to Q₇ are applied to the writing elements R₁₁ to R₁₇. Then, the shift direction switching pulse S₃ becomes "0" so that the AND gate G₄₃ is enabled and the recording signal S₀ goes to the input of the first shift register SR₁ to be shifted in the left, through the AND gate G₄₃. The shift direction switch pulse S₃ shifts the register SR₁ to the left so that the recording signals Q'₁ to Q'₇ are loaded into the position as shown. After this, the writing control pulse S₇ transfers the contents of the first shift register SR₁ to the second shift register SR₂, in parallel fashion, from which the contents are delivered to the second conductors L₇ to L₁. At this time the odd numbered unit recording block, e.g. UB₂, is selected and therefore the recording signals Q'₁ to Q'₇ are supplied to the recording elements R₂₁ to R₂₇.

While the description thus far described relates to the thermal recording apparatus, the invention may also be applied to electrostatic recording apparatuses, the discharge recording apparatuses and the like. 

What we claim is:
 1. A recording apparatus comprising:a recording head including a plurality of main blocks arranged in a given direction each main block having first and second unit recording blocks arranged in the given direction each unit recording block further including n recording units each recording unit further including a series-connected diode and recording element pair, a plurality of unit recording block selection terminals each of which is connected to one end of said n recording units, a plurality of first conductors for connecting the other ends of the ith (n≧i≧1) recording units of said first unit recording block with the other ends of the (N+1-i) recording units of said second unit recording block, and a plurality of second conductors for connecting commonly the corresponding first conductors among said main blocks and for supplying signals to be recorded to said recording units; and a drive circuit including first means for selecting a desired one of said unit recording blocks and second means for supplying recording signals in the order of said recording units arrangement to the recording units of said selected unit recording block.
 2. A recording apparatus according to claim 1, in which said recording element is a resistor for heat sensitive paper.
 3. A recording apparatus according to claim 1, in which said drive circuit includes: first means for selecting said unit recording blocks in the given order; and second means for inverting the order in which serially incoming recording signals are supplied to said second conductors each time said unit recording block selection is made.
 4. A recording apparatus according to claim 3, in which said second means includes: first and second shift registers each having n output stages into which said recording signals are loaded with shifting them therein in the same direction; means for supplying to a corresponding one of said second conductors the output of the ith (n≧i≧1) stage of said first shift register or the output of the (+1-i) th stage of said second shift register through OR gate means; and means for initiating loading of said recording signals into one of said shift registers upon completion of the loading of said recording signals into the other shift register while at the same time for coupling the outputs of the respective stages of said other shift register with said second conductors through said OR gate means.
 5. A recording apparatus according to claim 3, in which said second means includes: a first shift register with n output stages into which recording signals are loaded in serial fashion; a second shift register with n output stages coupled with said corresponding second conductors, into which the contents of said first shift register are loaded in serial fashion; and means for inverting the shift direction of said second shift register when the contents of said first shift register is transferred into said second shift register, each time the selection of said unit recording block is made.
 6. A recording apparatus according to claim 3, in which said second means includes: a first shift register with n output stages into which said recording signals are serially loaded; a second shift register with n output stages coupled with said corresponding second conductors, into which the contents of said first shift register is loaded in parallel manner; and means for inverting the shift direction of said first shift register when said recording signals are serially loaded into said first shift register, each time the selection of said unit recording block is made.
 7. A recording apparatus according to claim 1, in which said first conductors include a couple of first portions connected with the other ends of said recording units, and a second portion for connecting the free ends of said first portion and said first conductors are formed on an insulating substrate, said second conductors are provided in parallel with said second portion of said corresponding first conductors, through an insulating layer, and said second portion of said corresponding first conductor and said second conductors are connected through holes formed to said insulating layer.
 8. A recording apparatus according to claim 7, in which said first portions of said first conductors are all disposed in parallel, said second portions are disposed normal to said first portions, and said second conductors and said first conductors are connected at almost central portions of said second portions of said first conductors. 